Crown-slitting pliers



Dec. 23, 1930.

c? RADC') CROWN SLITTING PLIERS Filed July 11. 19.27

Char/0 6 Patented Dec. 23, 1930 UNITED STATES CHARLOS RAD, F BUDAPEST, HUNGARY onownssmrrme rLIERs Application filed July 11,1927, Serial No.

WVith the usual crown slitting pliers hither- V to the slitting knife is rigidly secured to the limbs of the pliers so that the knife in slitting describes an arcuate path. This path of the knife is very disadvantageous since upon slitting the solo and pillar crowns only the slitting force is necessary and the lateral bending pressure due to the curved path of the knife greatly enhances the risk of injury 19 of the tooth carrying the crown.

This disadvantage is removed by the use of the crown slitting pliers forming the subject of the invention, as with this the slitting knife by the intermediary of a guide does not describe a curved path but can only move positively up and down in a direction perpendicular to the supporting limb.

Three constructional forms of the invention are shown by way of example in the, accompanying drawing, wherein Fig. 1 is a side elevation of the open pliers, Fig. 2 is a side elevation of the pliers closed, Fig. 3 is a cross section of the pliers, Fig. l is a front elevation showing a secend embodiment of the invention; v Fig. 5 is a side elevation corresponding to Fig. 4e, and V Fig. 6 is a side elevation of a third embodiment of the invention.

With the constructional form according to Figs. 1-3 a is the supporting limb, b the pressure arm, and 0 the guide rails controlling the movement of the slitting knife d in the same direction and standing perpendicular to the supporting limb or to which they are secured, the length of said guide rails being equal to the usual length of the crowns. The legs of pliers are indicated at e, and the slitting knife (Z is loosely arranged in the free end of the pressure arm I; and is so drawn along the guide rails c that upon movement of the pressure arm it remains quite parallel to the supporting limb a and is positively moved up and down in this position. In consequence of I this construction the slitting knife does not produce any laterally acting force. The crown can thus be slit of and removed from the tooth carrying it without any danger of fracturing the latter. Moreover the knife does not produce any pressure upon the gums 204,991, and in Hungary August 7, 1926.

around the teeth and does not damage them.

With the constructional form according to Figs. 46 the end ofthe supporting limb a is trifurcated,which has the advantage that it affords a suitable support for a straight slitting knife or for one curved to the left or right. With the constructional form according to Fig. 5 a guide bar f is secured upon and perpendicular to the supporting .limb. In the free end of the pressure arm .6 is inserted a member 9 which runs parallel with the supporting limb a and in this member is provided a bore through which the bar 7 passes. On the end of the bar f is secured an abutment h. Pins 2' extend on both sides of the member 9 and project into a downwardly extending groove j formed in the arm 6. The slitting knife which may be straight or bent to the left or right is provided with a pin-like abutmentl which is inserted in a bore formed in 70 the member 9 and is secured therein by a screw m. Upon moving the pressure arm I), this moves the member 9 by means of the pin 2' and also the cutting knife inserted therein and guided by the bar f in a position parallel to the supporting limb a. IVith the construction according to Fig. 6 the member 9 is provided with a guide extension 0 which passes through an aperture in the supporting limb a and is provided at the endwith an abutment h. Upon movement of the pressure arm in this case the member 9 does not move upon the guide bar but the guide 0 integral therewith slides in the aperture of the supporting limb a, whereby the slitting lniife is caused 35 to move parallel to the supporting limb.

I claim In crown slitting pliers a pressure arm, a stripping knife fixed loosely on said pressure arm, a bar guide onto which said pressure arm is drawn, a supporting branch, said bar guide starting. from said supporting branch and connected with the stripping knife, pivots projecting on both sides, and a groove in the pressure arm, said pivots projecting into said 95 groove.

DR. GHARLOS RADO. 

